The present invention relates to a cleaning apparatus for magnetic tape, and more particularly to a cleaning apparatus for magnetic tape cut from a wide raw material web of magnetic tape into a magnetic tape in final-product form in a specific width.
Recently, magnetic tape has been widely used in many fields following improvements in various performance characteristics thereof. Magnetic tape is usually initially manufactured in the form of a wide raw material web of which is much wider than the magnetic tape of the final product. The wide raw material web is cut into magnetic tapes of specified predetermined widths in a cutting process.
In the cutting process, an apparatus to cut the wide raw material web of magnetic tape is obviously required. The product quality of the final product is strongly affected by the cutting quality, namely, by the accuracy and neatness of the cutting process. That is to say, if the cutting quality is poor, dust particles, which result from the shedding of magnetic powder or tape base material from the cut edges of the tape, may be generated in significant amounts. The dust particles are carried on the surface of the cut magnetic tape, causing many kinds of problems during usage such as signal drop-out during recording and reproducing or head clogging in the recording-reproducing apparatus. Moreover, even if such dust particles are not shed, depending upon the amount of deterioration of the cutting quality, the surface accuracy of the cut edges may be unacceptable, and the same problems such as occur in the case of dust particle generation arise during recording and reproducing.
Techniques have been proposed to remove the dust particles from the surface of the magnetic tape. A cleaning apparatus for magnetic tape such as disclosed in U.S. Pat. No. 4,213,222 has been applied to clean the surface of a tape by means of an unwoven material and a magnet after the tape has been cut into the predetermined width. As this apparatus was merely applied to clean the front and back surfaces of the cut tape, it was easy to ensure close contact between the cleaning device and the tape surface to be cleaned, even if the contact pressure exerted by the magnet on the tape was only roughly adjusted.
However, employing a cleaning apparatus of this kind to clean the tape edges is accompanied by another problem, namely, the pressure in the transverse direction used to achieve contact between the edges of the magnetic tape and the cleaning device cannot be satisfactorily regulated to hold the position of the tape edges within a desired range of tolerance. These pressure variations are due to variations in the tape tension during tape transport and fluctuations in the amount of friction between the magnetic tape and the tape guides. The edges of the tape can be damaged if the contact pressure between the edges and the cleaning device is too strong, and cleaning cannot be properly achieved if the contact pressure is too weak.
Especially for magnetic tapes used for video recording and reproduction, since the audio signal and the tracking signal must be recorded in side portions of the tape surface near the tape edges, the tape edge quality is very important to fully realize good tape performance.